1. Field of the Invention
This invention relates to a diesel engine crankcase lubricating composition which exhibits improved resistance to corrosion and oxidation. More particularly, this invention relates to a novel corrosion and oxidation resistant diesel engine crankcase lubricating composition comprising a major amount of a hydrocarbon lubricating oil and a minor amount of a reaction product prepared by first reacting a hydroxybenzoic acid with a polyoxyalkylene polyol to produce an ester, and thereafter reacting the esterification product with an aldehyde or ketone and a substituted or unsubstituted heterocyclic azole reactant to form the final reaction product. The instant invention is particularly useful as a lubricant in large diesel engines such as marine and railway diesel engines.
2. Information Disclosure Statement
As is well known to those skilled in the art, lubricating oils must be characterized by resistance to oxidation and corrosion inhibition. Since the oils used as lubricants in the crankcases of large diesel engines, such as marine and railway diesel engines, are subject to unique conditions of operation, special attention must be directed to the potential problems which are to be encountered.
One particular problem related to railway diesel engine oil is due to the practice in the railroad industry of mixing poorer grade fuels (such as marine residual) with the regular D-2 diesel fuel. While there is a savings associated with the use of these mixed fuels, engine performance problems such as increased corrosion and poorer oxidative stability often arise. In addition, the advent of new, more fuel efficient railway diesel engines has put a greater demand on the oxidation resistance of railway diesel lubricants. Oxidized lubricants lead to increased corrosive attack of engine metal surfaces; consequently, lubricants employed in newer railway diesel engines must be changed more frequently to prevent such corrosive attack.
In view of the above, diesel engine lubricant compositions have previously been specifically formulated containing anti-wear additives, demulsifying agents, oxidation and corrosion inhibitors and other additives. For example:
Co-assigned U. S. patent application Ser. No. 115,330, filed Nov. 2, 1987 (Sung et al.) discloses an oxidation and corrosion-resistant diesel engine lubricant composition comprising a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of an n-acyl sarcosine and a substituted or unsubstituted heterocyclic axole; PA1 Co-assigned U.S. patent application Ser. No. 945,599, filed Dec. 23, 1986 (Sung et al.) discloses a haze, oxidation, and corrosion-resistant diesel engine lubricant composition which comprises a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of an anhydride compound, a hydrocarbon-substituted mono primary amine or ether amine, and a nitrogen-containing hetercyclic azole or polyalkylene polyamine compound; PA1 Co-assigned U.S. Pat. No. 4,464,276 (Sung et al.) describes the preparation of novel polyoxyalkylene polyamine-triazle complexes and their use in diesel lubricant compositions as antioxidants and corrosion-inhibitors; PA1 Co-assigned U.S. Pat. No. 4,285,823 (Sung et al.) discloses a diesel engine lubricant composition comprising a corrosion inhibitor which is the reaction product of an N-alkyl-1,3 propane diamine, formaldehyde, and a 5-aminotetrazole; PA1 U.S. Pat. No. 3,791,971 (Lowe) discloses a lubricating oil composition comprising an additive which may be a polyol compound or a reaction product of a polyol compound and mono or polyisocyanates, mono or dicarboxylic acids, or acid halides and anhydrides; and PA1 U.S. Pat. No. 3,684,734 (Liebold et al.) discloses the use of the esterification product of (i) a polyoxyethylene-polyoxypropylene block copolymer and (ii) an aliphatic or aromatic hydroxycarboxylic acid as a demulsifier for crude oil emulsions. PA1 Co-assigned U.S. Pat. No. 4,551,152 (Sung) discloses a wear-inhibiting additive for motor fuel compositions which is obtained by reacting a polyol with a carboxy phenol to form an ester, and thereafter reacting the ester with an aldehyde or ketone and an N-alkyl-alkylene diamine; and PA1 Co-assigned U.S. Pat. No. 4,430,093 (Jenkins et al.) discloses a diesel fuel additive which is the reaction product of a polyol compound having a propylene oxide-ethylene oxide backbone and a benzophenone tetracarboxylic dianhydride.
The use of propylene oxide-ethylene oxide backbone polyol reaction products as additives in motor fuel compositions is also known to those skilled in the art. For example:
It is an object of this invention to provide a novel diesel engine lubricant composition. It is another object of this invention to provide a novel lubricant composition, suitable for use in large marine and railway diesel engines, characterized by its resistance to oxidation and corrosion. It is yet another object of this invention to provide a method of preparing such a diesel engine lubricant composition.
It is a feature of this invention that a diesel engine lubricant comprising a major amount of a hydrocarbon lubricating oil and a minor amount of the reaction product of the instant invention is characterized by its resistance to oxidation and corrosion. It is another feature of this invention that such a diesel engine lubricant composition is particularly suitable for use in large marine and railway diesel engines.
It is an advantage of this invention that the corrosion of diesel engine metal surfaces is reduced by employing this invention as a lubricant. It is another advantage that lubricants of the instant invention may be changed less frequently than other conventional diesel engine lubricants. It is yet another advantage that lubricants of the instant invention tend to resist oxidation and viscosity increase when contaminated with marine residual fuel.